Certain 3-benzoyl-4-oxolactams

ABSTRACT

Compounds having the formula ##STR1## wherein R is halogen; C 1  -C 2  alkyl; C 1  -C 2  alkoxy; nitro; cyano; C 1  -C 2  haloalkyl; or R a  SO n  --wherein n is 0 or 2 and R a  is C 1  -C 2  alkyl; R 1  is hydrogen or C 1  -C 4  alkyl; R 2  is hydrogen or C 1  -C 4  alkyl; or R 1  and R 2  together are alkylene having 2-5 carbon atoms; R 3  is hydrogen or C 1  -C 4  alkyl; R 4  is hydrogen or C 1  -C 4  alkyl; or R 3  and R 4  together are carbonyl; and R 5  and R 6  independently are (1) hydrogen; (2) halogen; (3) C 1  -C 4  alkyl; (4) C 1  -C 4  alkoxy; (5) trifluoromethoxy; (6) cyano; (7) nitro; (8) C 1  -C 4  haloalkyl; (9) R b  SO m  --wherein m is the integer 0, 1 or 2; and R b  is (a) C 1  - C 4  alkyl; (b) C 1  -C 4  alkyl substituted with halogen or cyano; (c) phenyl; or (d) benzyl; (10) --NR c  R d  wherein R c  and R d  independently are hydrogen or C 1  -C 4  alkyl; (11) R e  C(O)--wherein R e  is C 1  -C 4  alkyl or C 1  -C 4  alkoxy; or (12) --SO 2  NR c  R d  wherein R c  and R d  are as defined; and (13) --N(R c )C(O)R d  wherein R c  and R d  are as defined; R 7  is C 1  -C 4  alkyl or phenyl; and t is the integer 0 or 1 and their salts are useful as herbicides.

CROSS REFERENCE TO RELATED APPLICATION

This is a divisional of application Ser. No. 021,811, filed Mar. 13,1987, now U.S. Pat. No. 4,808,720 which is a continuation-in-part ofapplication Ser. No. 871,973, filed June 9, 1986, now abandoned.

BACKGROUND OF THE INVENTION

The compound having the structural formula ##STR2## wherein the nitrosubstituent is in the 3- or 4-position are described in J. HeterocyclicChem., 6(1), pp. 13-22 (1969). No utility for these compounds is taught.

Compounds of the structural formula ##STR3## wherein X is halogen, CF₃,alkyl, nitro, cyano or alkoxy are described in European patentapplication publication No. 40 082 (1981). The compounds areintermediates for the preparation of certain substituted oxonicotinates.

DESCRIPTION OF THE INVENTION

This invention relates to certain 3-benzoyl-4-oxolactams and their saltsand their use as herbicides.

One embodiment of this invention is an herbicidal composition comprisingan herbicidally active 3-benzoyl-4-oxolactam and an inert carriertherefor wherein the 2-position of the benzoyl moiety is substitutedwith halogen; C₁ -C₂ alkyl, preferably methyl; C₁ -C₂ alkoxy, preferablymethoxy; nitro; cyano; C₁ -C₂ haloalkyl, preferably trifluoromethyl orR^(a) SO_(n) -- wherein R^(a) is C₁ -C₂ alkyl, preferably methyl and nis the integer 0 or 2, preferably 2; and the 4-position preferably issubstituted with an electron withdrawing group, such as halogen, cyanoor trifluoromethyl. The 5- or 6-positions of the 4-oxolactam moiety canbe substituted, preferably with the groups hereinafter recited. The1-position of the 4-oxolactam moiety is preferably substituted with C₁-C₄ alkyl. The 3-, 4-, 5- and 6-positions of the benzoyl moiety can besubstituted, preferably with the groups hereinafter recited.

Also embodied within the scope of this invention are novel compoundshaving the following structural formula ##STR4## wherein R is halogen,C₁ -C₂ alkyl, preferably methyl; C₁ -C₂ alkoxy, preferably methoxy;nitro; cyano; C₁ -C₂ haloalkyl, preferably trifluoromethyl; or R^(a)SO_(n) -- wherein R^(a) is C₁ -C₂ alkyl, preferably methyl and n is theinteger 0 or 2, preferably 2;

R¹ is hydrogen or C₁ -C₄ alkyl, preferably C₁ -C₂ alkyl, more preferablymethyl, most preferably R¹ is hydrogen or methyl;

R² is hydrogen; C₁ -C₄ alkyl, preferably C₁ -C₂ alkyl, more preferablymethyl most preferably R² is hydrogen or methyl; or

R³ is hydrogen or C₁ -C₄ alkyl, preferably C₁ -C₂ alkyl, more preferablymethyl; most preferably R³ is hydrogen or methyl;

R⁴ is hydrogen or C₁ -C₄ alkyl, preferably C₁ -C₂ alkyl, more preferablymethyl; most preferably R⁴ is hydrogen or methyl; or

R³ and R⁴ together are carbonyl; or

R¹ and R² together are alkylene having 2-5 carbon atoms; or

R⁵ and R⁶ independently are (1) hydrogen; (2) halogen, preferablychlorine, fluorine or bromine; (3) C₁ -C₄ alkyl, preferably methyl; (4)C₁ -C₄ alkoxy, preferably methoxy; (5) trifluoromethoxy; (6) cyano; (7)nitro; (8) C₁ -C₄ haloalkyl, more preferably trifluoromethyl; (9) R^(b)SO_(m) -- wherein m is the integer 0, 1 or 2, preferably 2; and

R^(b) is

(a) C₁ -C₄ alkyl, preferably methyl;

(b) C₁ -C₄ alkyl substituted with halogen or cyano, preferablychloromethyl, trifluoromethyl or cyanomethyl;

(c) phenyl; or

(d) benzyl;

(10) --NR^(c) R^(d) wherein

R^(c) and R^(d) independently are hydrogen or C₁ -C₄ alkyl;

(11) R^(e) C(O)-- wherein

R^(e) is C₁ -C₄ alkyl or C₁ -C₄ alkoxy;

(12) --SO₂ NR^(c) R^(d) wherein R^(c) and R^(d) are as defined; and

(13) --N(R^(C))C(O)R^(d) wherein R^(c) and R^(d) are as defined;

R⁷ is C₁ -C₄ alkyl, preferably C₁ -C₂ alkyl or phenyl; and t is theinteger 0 or 1, preferably 1.

The term "C₁ -C₄ alkyl" includes methyl, ethyl, n-propyl, isopropyln-butyl, sec-butyl, isobutyl and t-butyl. The term "halogen" includeschlorine, bromine, iodine and fluorine. The term "C₁ -C₄ alkoxy"includes methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy,isobutoxy and t-butoxy. The term "C₁ -C₄ haloalkyl" includes the alkylgroups defined above under C₁ -C₄ alkyl in which one or more hydrogensis replaced by chloro, bromo, iodo or fluoro.

Preferably, R⁵ is in the 3-position. Most preferably R⁵ is hydrogen andit is in the 3-position. Preferably R⁶ is in the 4-position. Morepreferably, R⁶ is hydrogen, chlorine, cyano, fluorine, trifluoromethylor R^(b) SO₂ wherein R^(b) is C₁ -C₄ alkyl, preferably methyl or C₁ -C₄haloalkyl, preferably chloromethyl, difluoromethyl or trifluoromethyl.

Salts of the above-described compounds (as defined hereinafter) areincluded within the scope of the instant invention.

The compounds of this invention can have the following three structuralformulae because of tautomerism: ##STR5## wherein R, R¹, R², R³, R⁴, R⁵,R⁶, R⁷ and t are as defined above.

The circled proton on each of the three tautomers is reasonably labile.These protons are acidic and can be removed by reaction with a base toform a salt having an anion of the following three resonance forms:##STR6## wherein R, R¹, R², R³, R⁴, R⁵, R⁶, R⁷ and t are as definedabove.

Examples of cations of these bases are inorganic cations such as alkalimetals, e.g. lithium, sodium and potassium; the alkaline earth metals,e.g. calcium and magnesium or ammonium or organic cations such assubstituted ammonium, sulfonium, sulfoxonium or phosphonium wherein thesubstituents are aliphatic or aromatic groups.

Those skilled in the art will recognize in considering the salts of thisinvention that varying degrees of association between the anion andcation will exist depending upon the nature of the cation. In someinstances with a suitable cation, such as copper, the salt can exist ina chelated form.

The compounds of this invention and their salts are active herbicides ofa general type. That is, they are herbicidally effective against a widerange of plant species. The method of controlling undesirable vegetationof the present invention comprises applying an herbicidally effectiveamount of the above described compounds to the area where control isdesired.

The compounds of the present invention can be prepared by the followingtwo-step general method.

The process proceeds via the production of an enol ester intermediate asshown in reaction (1). The final product is obtained by rearrangement ofthe enol ester as shown in reaction (2). The two reactions may beconducted as separate steps by isolation and recovery of the enol esterusing conventional techniques prior to conducting step (2), or byaddition of a cyanide source to the reaction medium after the formationof the enol ester, or in one step by inclusion of the cyanide source atthe start of reaction (1). ##STR7## wherein t and R through R⁷ are asdefined and Y is halogen, preferably chlorine, C₁ -C₄ alkyl--C(O)--O--,C₁ -C₄ alkoxy--C(O)--O-- or ##STR8## wherein R, R⁵ and R⁶ in thisportion of the molecule are identical with those in the reactant shownabove and the moderate base is as defined, preferably tri-C₁ -C₆alkylamine, alkali metal carbonate or alkali metal phosphate.

Generally, in step (1) mole amounts of the oxolactam and substitutedbenzoyl reactant are used, along with a mole amount or excess of thebase. The two reactants are combined in an organic solvent such asmethylene chloride, toluene, ethyl acetate or dimethylformamide. Thebase or benzoyl reactant preferably are added to the reaction mixturewith cooling. The mixture is stirred at 0° C.-50° C. until the reactionis substantially complete.

The reaction product is worked up by conventional techniques. ##STR9##wherein t and R through R⁷ are as defined.

Generally, in step (2) a mole of the enol ester intermediate is reactedwith 1 to 4 moles of the base, preferably about 2 moles of moderate baseand from 0.01 mole to about 0.5 mole or higher, preferably about 0.1mole of the cyanide source (e.g., potassium cyanide or acetonecyanohydrin). The mixture is stirred in a reaction pot until therearrangement is substantially complete at a temperature below 80° C.,preferably about 20° C. to about 40° C., and the desired product isrecovered by conventional technques.

The term "cyanide source" refers to a substance or substances whichunder the rearrangement conditions consists of or generates hydrogencyanide and/or cyanide anion.

The process is conducted in the presence of a catalytic amount of asource of cyanide anion and/or hydrogen cyanide, together with a molarexcess, with respect to the enol ester, of a moderate base.

Preferred cyanide sources are alkali metal cyanides such as sodium andpotassium cyanide; cyanohydrins of methyl alkyl ketones having from 1-4carbon atoms in the alkyl groups, such as acetone or methyl isobutylketone cyanohydrins; cyanohydrins of benzaldehyde or of C₂ -C₅ aliphaticaldehydes such as acetaldehyde, propionaldehyde, etc., cyanohydrins;zinc cyanide; tri(lower alkyl) silyl cyanides, notably trimethyl silylcyanide; and hydrogen cyanide itself. Hydrogen cyanide is consideredmost advantageous as it produces relatively rapid reaction and isinexpensive. Among cyanohydrins the preferred cyanide source is acetonecyanohydrin.

When salts are used as the active ingredient in the herbicidalcompositions of this invention, it is recommended to use salts that areagriculturally acceptable.

The phytotoxic compositions of this invention can also contain otheradditives, for example, fertilizers, other herbicides and otherpesticides, used as adjuvant or in combination with any of theabovedescribed adjuvants. Fertilizers useful in combination with theactive ingredients include, for example, ammonium nitrate, urea andsuperphosphate.

The cyanide source is used in an amount up to about 50 mole percentbased on the enol ester. It may be used in as little as about 1 molepercent to produce an acceptable rate of reaction at about 40 C. on asmall scale. Larger scale reactions give more reproducible results withslightly higher catalyst levels of about 2 mole percent. Generally about1-10 mole % of the cyanide source is preferred.

The process is conducted with a molar excess, with respect to the enolester, of a moderate base. By the term "moderate base" is meant asubstance which acts as a base yet whose strength or activity as a baselies between that of strong bases such as hydroxides (which could causehydrolysis of the enol ester) and that of weak bases such asbicarbonates (which would not function effectively). Moderate basessuitable for use in this embodiment include both organic bases such astertiary amines and inorganic bases such as alkali metal carbonates andphosphates. Suitable tertiary amines include trialkylamines such astriethylamine. Suitable inorganic bases include potassium carbonate andtrisodium phosphate.

The base is used in an amount of from about 1 to about 4 moles per moleof enol ester, preferably about 2 moles per mole.

When the cyanide source is an alkali metal cyanide, particularlypotassium cyanide, a phase transfer catalyst may be included in thereaction. Particularly suitable phase transfer catalysts are the Crownethers.

A number of different solvents are useful in this process, depending onthe nature of the acid chloride or the acylated product. A preferredsolvent for this reaction is acetonitrile. Other solvents which may beemployed, depending on the reactants or products include toluene,1,2-dichloroethane, methylene chloride, ethyl acetate,dimethylformamide, and methyl isobutyl ketone (MIBK).

In general, depending on the nature of the reactants and the cyanidesource, the rearrangement may be conducted at temperature up to about50° C.

The above described substituted benzoyl chlorides can be prepared fromthe corresponding substituted benzoic acids according to the teaching ofReagents for Organic Synthesis, Vol. I, L. F. Fieser and M. Fieser, pp.767-769 (1967). ##STR10## wherein R, R⁵ and R⁶ are as previouslydefined.

The substituted benzoic acids can be prepared by a wide variety ofgeneral methods according to the teaching of The Chemistry of CarboxylicAcids and Esters, S. Patai, editor, J. Wiley and Sons, New York, N.Y.(1969) and Survey of Organic Synthesis, C. A. Buehler and D. F. Pearson,J. Wiley and Sons, (1970).

The following are three representative examples of the methods describedtherein. ##STR11## wherein R, R⁵ and R⁶ are as previously defined.

In reaction (a) the substituted benzonitrile is heated to reflux inaqueous sulfuric acid for several hours. The mixture is cooled and thereaction product is isolated by conventional techniques. ##STR12##wherein R, R⁵ and R⁶ are as previously defined.

In reaction (b) the substituted acetophenone is heated to reflux forseveral hours in an aqueous hypochlorite solution. The mixture is cooledand the reaction product is isolated by conventional techniques.##STR13## wherein R, R⁵ and R⁶ are as defined and X is chlorine, bromineor iodine.

The substituted aromatic halide is allowed to react with magnesium in asolvent such as ether. The solution is then poured over crushed dry iceand the benzoic acid is isolated by conventional techniques.

The above-described 4-oxolactams can be prepared according to theteaching of V. J. Lee et al., J. American Chem. Soc., 100, 4225-4236(1978).

The following example teaches the synthesis of a representative compoundof this invention.

EXAMPLE 1 3-(2-Nitro-4-chlorobenzoyl)-1,5-dimethyl-4-oxovalerolactam##STR14##

2-Nitro-4-chlorobenzoyl chloride (3.7 g, 17 mmol) and1,5-dimethyl-4-oxovalerolactam (3.0 g, 17 mmol) were dissolved in 150 mlmethylene chloride. Triethylamine (1.7 g, 17 mmol) was added and theresulting solution was stirred at room temperature for fifteen minutes.The solution was washed with dilute hydrochloric acid, 5% potassiumcarbonate and saturated sodium chloride, dried over magnesium sulfateand concentrated under vacuum. The residue was dissolved in 20 ml ofacetonitrile. Triethylamine (1.7 g, 17 mmol) potassium cyanide (0.1 g,1.5 mmol) and 18-crown-6 (0.1 g, 0.4 mmol) were added and the mixturestirred at room temperature for 20 minutes. After dilution with ether,the solution was washed with dilute hydrochloric acid and extracted with5% potassium carbonate. The basic extract was acidified withhydrochloric acid and extracted with chloroform. The chloroform extractwas washed with 10% cupric acetate, water, saturated sodium bicarbonate,and 2N hydrochloride acid. The chloroform layer was washed with water,dried ovr MgSO₄ and evaporated to yield a yellow solid (2.0 g, m.p.119°-120° C.) which was identified as the desired compound by nuclearmagnetic resonance spectroscopy, infrared spectroscopy and massspectroscopy.

The following is a table of certain selected compounds that arepreparable according to the procedure described hereto. Compound numbersare assigned to each compound and are used throughout the remainder ofthe application.

                                      TABLE I                                     __________________________________________________________________________     ##STR15##                                                                    Comp.                                                                         No. R  R.sup.1                                                                          R.sup.2                                                                          R.sup.3                                                                          R.sup.4                                                                          R.sup.5                                                                            R.sup.6                                                                              R.sup.7                                                                              t m.p. °C.                       __________________________________________________________________________    1   NO.sub.2                                                                         H  H  H  H  H    4-Cl   n-C.sub.3 H.sub.7                                                                    1 oil                                   2   NO.sub.2                                                                         H  H  n/a                                                                              n/a                                                                              H    4-Cl   n-C.sub.3 H.sub.7                                                                    0 oil                                   3   Cl H  H  H  H  H    4-SO.sub.2 CH.sub.3                                                                  n-C.sub.3 H.sub.7                                                                    1 oil                                   4   NO.sub.2                                                                         H  H  H  H  H    4-Cl   C.sub.2 H.sub.5                                                                      1 oil                                   5   NO.sub.2                                                                         CH.sub.3                                                                         H  H  H  H    4-Cl   C.sub.2 H.sub.5                                                                      1 100-107                               6(a)                                                                              NO.sub.2                                                                         CH.sub.3                                                                         H  H  H  H    4-Cl   CH.sub.3                                                                             1 119-120                               7   NO.sub.2                                                                         H  H  CH.sub.3                                                                         CH.sub.3                                                                         H    4-Cl   CH.sub.3                                                                             1 130-131                               8   NO.sub.2                                                                         H  H  H  H  H    4-CN   C.sub.2 H.sub.5                                                                      1 159-160                               9   CH.sub.3                                                                         H  H  H  H  3-NO.sub.2                                                                         H      C.sub.2 H.sub.5                                                                      1 oil                                   10  CF3                                                                              H  H  CH.sub.3                                                                         CH.sub.3                                                                         H    4-CF.sub.3                                                                           CH.sub.3                                                                             1 86-90                                 11  NO.sub.2                                                                         H  H  CH.sub.3                                                                         H  H    4-Cl   CH.sub.3                                                                             1 142-143                               12  NO.sub.2                                                                         CH.sub.3                                                                         H  H  H  H    4-SO.sub.2 CH.sub.2 Cl                                                               C.sub.2 H.sub.5                                                                      1 oil                                   13  NO.sub.2                                                                         H  H  H  H  H    4-SO.sub.2 CH.sub.2 Cl                                                               C.sub.2 H.sub.5                                                                      1 oil                                   14  NO.sub.2                                                                         CH.sub.3                                                                         H  H  H  H    4-SO.sub.2 CH.sub.2 Cl                                                               CH.sub.3                                                                             1 141-142                               15  NO.sub.2                                                                         CH.sub.3                                                                         H  H  H  H    4-SO.sub.2 CH.sub.3                                                                  C.sub.2 H.sub.5                                                                      1 oil                                   16  NO.sub.2                                                                         CH.sub.3                                                                         H  H  H  H    4-SO.sub.2 CH.sub.3                                                                  CH.sub.3                                                                             1 semi-solid                            17  Cl CH.sub.3                                                                         H  H  H  3-OC.sub.2 H.sub.5                                                                 4-SO.sub.2 C.sub.2 H.sub.5                                                           CH.sub. 3                                                                            1 oil                                   18  NO.sub.2                                                                         CH.sub.3                                                                         CH.sub.3                                                                         CH.sub.3                                                                         H  H    4-Cl   CH.sub.3                                                                             1 oil                                   19  NO.sub.2                                                                         CH.sub.3                                                                         CH.sub.3                                                                         H  H  H    4-SO.sub.2 CH.sub.2 Cl                                                               CH.sub.3                                                                             1 oil                                   20  NO.sub.2                                                                         CH.sub.3                                                                         CH.sub.3                                                                            H  H    4-SO.sub.2 CH.sub.3                                                                  CH.sub.3                                                                             1 178-179                               21  CH.sub.3                                                                         CH.sub.3                                                                         H  H  H  3-NO.sub.2                                                                         H      C.sub.2 H.sub.5                                                                      1 semi-solid                            22  NO.sub.2                                                                         H  H  H  H  H    4-Cl                                                                                  ##STR16##                                                                           1 154 dec.                              23  NO.sub.2                                                                         H  H  H  H  H    4-Cl   i-C.sub.3 H.sub.7                                                                    1 83-85                                 24  NO.sub.2                                                                         H  H  H  H  H    4-SO.sub.2 CH.sub.2 Cl                                                               i-C.sub.3 H.sub.7                                                                    1 oil                                   25  NO.sub.2                                                                         H  H  H  H  H    4-Cl   n-C.sub.4 H.sub.9                                                                    1 oil                                   26  NO.sub.2                                                                         H  H  H  H  H    4-SO.sub.2 CH.sub.2 Cl                                                               n-C.sub.4 H.sub.9                                                                    1 oil                                   27  NO.sub.2                                                                         CH.sub.3                                                                         CH.sub.3                                                            O-                 H    4-Cl   CH.sub.3                                                                             1 oil                                   28  Cl CH.sub.3                                                                         CH.sub.3                                                            O-  H  4-SO.sub.2 CH.sub.3                                                              CH.sub.3                                                                         1     oil                                                        29  Cl CH.sub.3                                                                         CH.sub.3                                                            O-  3-OC.sub.2 H.sub.5                                                               4-SO.sub.2 C.sub.2 H.sub.5                                                       CH.sub.3                                                                         1     oil                                                        30  NO.sub.2                                                                         CH.sub.3                                                                         CH.sub.3                                                            O-  H  4-Cl                                                                             C.sub.2 H.sub.5                                                                  1     oil                                                        31  CH.sub.3                                                                         CH.sub.3                                                                         CH.sub.3                                                            O-  3-NO.sub.2                                                                       H  n-C.sub.3 H.sub.7                                                                1     oil                                                        32  NO.sub.2                                                                         CH.sub.3                                                                         CH.sub.3                                                            O-  H  4-Cl                                                                             C.sub.2 H.sub.5                                                                  1     oil                                                        33  CH.sub.3                                                                         CH.sub.3                                                                         CH.sub.3                                                            O-  3-NO.sub.2                                                                       H  CH.sub.3                                                                         1     oil                                                        34  NO.sub.2                                                                         C.sub.2 H.sub.5                                                                  CH.sub.3                                                            O-  H  4-Cl                                                                             CH.sub.3                                                                         1     semi-solid                                                 35  CH.sub.3                                                                         C.sub.2 H.sub.5                                                                  CH.sub.3                                                            O-  3-NO.sub.2                                                                       H  CH.sub.3                                                                         1     oil                                                        36  NO.sub.2                                                                         CH.sub.3                                                                         H  H  H  H    4-Cl   n-C.sub.3 H.sub.7                                                                    1 oil                                   37  NO.sub.2                                                                         CH.sub.3                                                                         H  H  H  H    4-CF.sub.3                                                                           n-C.sub.3 H.sub.7                                                                    1 oil                                   __________________________________________________________________________     (a) Prepared in Example I.                                                    n/a = Not applicable when t = 0.                                         

Herbicidal Screening Test

As previously mentioned, the herein described compounds produced in theabove-described manner are phytotoxic compounds which are useful andvaluable in controlling various plant species. Selected compounds ofthis invention were tested as herbicides in the following manner.

Pre-emergence herbicide test. On the day preceding treatment, seeds ofseven different weed species are planted in loamy sand soil inindividual rows using one species per row across the width of a flat.The weeds used are green foxtail (FT) (Setaria viridis), watergrass (WG)(Echinochloa crusgalli), wild oat (WO) (Avena fatua), annualmorningglory (AMG) (Ipomoea lacunosa), velvetleaf (VL) (Abutilontheophrasti), Indian mustard (MD) (Brassica juncea) and yellow nutsedge(YNG) (Cyperus esculentus). Ample seeds are planted to give about 20 to40 seedings per row, after emergence, depending upon the size of theplants.

Using an analytical balance, 600 milligrams (mg) of the compound to betested are weighed out in a piece of glassine weighing paper. The paperand compound are placed in a 60 milliliter (ml) wide-mouth clear bottleand dissolved in 45 ml of acetone or substituted solvent. Eighteen ml ofthis solution are transferred to a 60 ml wide-mouth clear bottle anddiluted with 22 ml of a water and acetone mixture (19:1) containingenough polyoxyethylene sorbitan monolaurate emulsifier to give a finalsolution of 0.5% (v/v). The solution is then sprayed on a seeded flat ona linear spray table calibrated to deliver 80 gallons per acre (748L/ha). The application rate is 4 lb/acre (4.48 Kg/ha).

After treatment, the flats are placed in the greenhouse at a temperatureof 70° to 80° F. and watered by sprinkling. Two weeks after treatment,the degree of injury or control is determined by comparison withuntreated check plants of the same age. The injury rating from 0 to 100%is recorded for each species as percent control with 0% representing noinjury and 100% representing complete control.

The results of the tests are shown in the following Table II.

                  TABLE II                                                        ______________________________________                                        Pre-Emergence Herbicidal Activity                                             Application Rate-4.48 kg/ha                                                   Cmpd.                                                                         No.   FT      WG      WO    AMG   VL    MD   YNG                              ______________________________________                                        1     100     100     90    100   100   100  80                               2     90      100     30    50    100   100  80                               3     100     100     80    100   100   100  80                               4     100     100     90    100   100   100  80                               5     100     100     100   20    100   100  80                               6     100     100     100   100   100   100  80                               7     100     100     100   100   100   100  80                               8     30      50      20    40    100   100  80                               9     30      80      30    5     60    80   70                               10    100     90      20    10    90    100  80                               11    100     100     95    100   100   100  80                               12    100     100     100   100   100   100  80                               13    100     100     100   100   100   100  80                               14    100     100     100   100   100   100  80                               15    100     100     100   100   100   100  80                               16    100     95      100   100   100   100  80                               17    100     100     100   100   100   100  80                               18    100     90      100   100   95    100  80                               19    100     90      100   100   95    90   80                               20    100     90      100   100   100   75   80                               21    100     95      100   100   100   80   80                               22    85      30      20    100   100   10   60                               23    100     80      100   100   100   100  80                               24    100     60      100   100   100   100  80                               25    100     100     100   100   100   20   80                               26    100     100     100   100   100   100  80                               27    100     90      100   100   100   100  90                               28    100     80      100   100   100   100  90                               29    100     100     100   100   100   100  90                               30    100     95      100   100   100   100  80                               31    100     100     30    80    100   100  30                               32    100     100     100   100   100   100  80                               33    100     95      20    90    100   100  80                               34    100     90      20    20    100   100  70                               35    85      10      0     20    100   100  30                               36    100     100     100   20    100   100  80                               37    100     100     90    100   100   100  80                               ______________________________________                                    

Post-Emergence Herbicide Test: This test is conducted in an identicalmanner to the testing procedure for the pre-emergence herbicide test,except the seeds of the seven different weed species are planted 10-12days before treatment. Also, watering of the treated flats is confinedto the soil surface and not to the foliage of the sprouted plants.

The results of the post-emergence herbicide test are reported in TableIII.

                  TABLE III                                                       ______________________________________                                        Post-Emergence Herbicidal Activity                                            Application Rate-4.48 kg/ha                                                   Cmpd.                                                                         No.   FT      WG      WO    AMG   VL    MD   YNG                              ______________________________________                                        1     100     100     60    75    90    80   30                               2     10      70      10    10    80    30   30                               3     50      60      60    50    50    50   70                               4     100     100     90    90    100   90   60                               5     100     100     90    100   100   100  80                               6     100     95      85    100   100   80   80                               7     90      85      80    80    90    80   80                               8     30      20      40    40    60    50   0                                9     80      60      80    10    90    60   30                               10    80      80      80    50    90    90   80                               11    90      80      80    80    90    80   80                               12    90      80      70    80    90    80   60                               13    100     85      80    80    90    90   70                               14    80      80      60    80    80    80   80                               15    95      80      70    80    80    80   80                               16    100     80      85    80    90    80   80                               17    90      60      80    80    80    80   80                               18    100     80      80    80    80    60   60                               19    85      65      70    80    80    60   60                               20    70      50      60    80    80    60   50                               21    60      50      40    60    60    40   30                               22    10      10      20    85    85    75   30                               23    60      80      90    90    90    80   70                               24    10      10      60    80    80    60   30                               25    100     90      90    90    90    60   50                               26    100     80      90    100   100   95   30                               27    100     100     100   100   100   100  90                               28    85      90      95    100   100   100  80                               29    100     100     100   100   100   100  80                               30    100     100     100   100   100   100  80                               31    80      30      30    100   100   100  30                               32    100     100     100   100   100   100  100                              33    100     80      100   100   100   100  65                               34    100     30      30    100   100   100  30                               35    0       0       0     70    100   100  0                                36    100     100     100   90    100   100  70                               37    100     100     100   100   100   100  80                               ______________________________________                                    

The compounds of the present invention and their salts are useful asherbicides and can be applied in a variety of ways at variousconcentrations. In practice, the compounds or salts are formulated intoherbicidal compositions, by admixture, in herbicidally effectiveamounts, with the adjuvants and carriers normally employed forfacilitating the dispersion of active ingredients for agriculturalapplications, recognizing the fact that the formulation and mode ofapplication of a toxicant may affect the activity of the materials in agiven application. Thus, these active herbicidal compounds or salts canbe formulated as granules of relatively large particle size, as wettablepowders, as emulsifiable concentrates, as powdery dusts, as flowables,as solutions or as any of several other known types of formulations,depending upon the desired mode of application. These formulations maycontain as little as about 0.5% to as much as about 95% or more byweight of active ingredient. A herbicidally effective amount dependsupon the nature of the seeds or plants to be controlled and the rate ofapplication varies from about 0.01 to approximately 10 pounds per acre,preferably from about 0.02 to about 4 pounds per acre.

Wettable powders are in the form of finely divided particles whichdisperse readily in water or other dispersants. The wettable powder isultimately applied to the soil either as a dry dust or as a dispersionin water or other liquid. Typical carriers for wettable powders includefuller's earth, kaolin clays, silicas and other readily wet organic orinorganic diluents. Wettable powders normally are prepared to containabout 5% to about 95% of the active ingredient and usually also containa small amount of wetting, dispersing, or emulsifying agent tofacilitate wetting and dispersion.

Emulsifiable concentrates are homogeneous liquid compositions which aredispersible in water or other dispersant, and may consist entirely ofthe active compound or salt with a liquid or solid emulsifying agent, ormay also contain a liquid carrier, such as xylene, heavy aromaticnaphthal, isophorone and other non-volatile organic solvents. Forherbicidal application, these concentrates are dispersed in water orother liquid carrier and normally applied as a spray to the area to betreated. The percentage by weight of the essential active ingredient mayvary according to the manner in which the composition is to be applied,but in general comprises about 0.5% to 95% of active ingredient byweight of the herbicidal composition.

Granular formulations wherein the toxicant is carried on relativelycoarse particles, are usually applied without dilution to the area inwhich suppression of vegetation is desired. Typical carriers forgranular formulations include sand, fuller's earth, attapulgite clay,bentonite clays, montmorillonite clay, vermiculite, perlite and otherorganic or inorganic materials which absorb or which may be coated withthe toxicant. Granular formulations normally are prepared to containabout 5% to about 25% active ingredients which may includesurface-active agents such heavy aromatic naphthas, kerosene or otherpetroleum fractions, or vegetable oils; and/or stickers such asdextrins, glue or synthetic resins.

Typical wetting, dispersing or emulsifying agents used in agriculturalformulations include, for example, the alkyl and alkylaryl sulfonatesand sulfates and their salts; polyhydric alcohols; polyethoxylatedalcohols; esters and fatty amines; and other types of surface-activeagents, many of which are available in commerce. The surface-activeagent, when used, normally comprises from 0.1% to 15% by weight of theherbicidal composition.

Dusts, which are free-flowing admixtures of the active ingredient withfinely divided solid such as talc, clays, flours and other organic andinorganic solids which act as dispersants and carriers for the toxicant,are useful formulations for soil-incorporating application.

Pastes, which are homogeneous suspensions of a finely divided solidtoxicant in a liquid carrier such as water or oil, are employed forspecific purposes. These formulations normally contain about 5% to about95% of active ingredient by weight, and may also contain small amountsof a wetting, dispersing or emulsifying agent to facilitate dispersion.For application, the pastes are normally diluted and applied as a sprayto the area to be affected.

Other useful formulations for herbicidal applications include simplesolutions of the active ingredient in a dispersant in which it iscompletely soluble at the desired concentration, such as acetone,alkylated naphthalenes, xylene and other organic solvents. Pressurizedsprays, typically aerosols, wherein the active ingredient is dispersedin finely-divided form as a result of vaporization of a low boilingdispersant solvent carrier, such as the Freons, may also be used.

The phytotoxic compositions of this invention can be applied to theplants in the conventional manner. Thus, the dust and liquidcompositions can be applied to the plant by the use of power-dusters,boom and hand sprayers and spray dusters. The compositions can also beapplied from airplanes as a dust or a spray or by rope wick applicationsbecause they are effective in very low dosages. In order to modify orcontrol growth of germinating seeds or emerging seedlings, as a typicalexample, the dust and liquid compositions can be applied to the soilaccording to conventional methods and can be distributed in the soil toa depth of at least 1/2 inch below the soil surface. It is not necessaythat the phytotoxic compositions be mechanically admixed with the soilparticles since these compositions can also be applied merely byspraying or sprinkling the surface of the soil. The phytotoxiccompositions of this invention can also be applied by addition toirrigation water supplied to the field to be treated. This method ofapplication permits the penetration of the compositions into the soil asthe water is absorbed therein. Dust compositions, granular compositionsor liquid formulations applied to the surface of the soil can bedistributed below the surface of the soil by conventional means such asdiscing, dragging or mixing operations. In the following examples theherbicidal compound can be substituted with the herbicidal salt of thecompound.

    ______________________________________                                        EMULSIFIABLE CONCENTRATE FORMULATIONS                                         General Formula with Ranges                                                                     Specific Formula                                            ______________________________________                                        Herbicidal  5-55      herbicidal    24                                        compound              compound                                                surfactant(s)                                                                             5-25      proprietary   10                                                              blend of oil-                                           solvent(s)  20-90     soluble                                                             100%      sulfonates and                                                                polyoxyethylene                                                               ethers                                                                        polar solvent 27                                                              petroleum     39                                                              hydrocarbon                                                                                 100%                                      WETTABLE POWDER FORMULATIONS                                                  herbicidal  3-90      herbicidal    80                                        compound              compound                                                wetting agent                                                                             0.5-2     sodium dialkyl                                                                              0.5                                                             naphthalene                                             dispersing agent                                                                          1-8       sulfonate                                               diluent(s)  8.5-87    sodium        7                                                     100%      lignosulfonate                                                                              7                                                               attapulgite clay                                                                            12.5                                                                          100%                                      EXTRUDED GRANULAR FORMULATIONS                                                herbicidal  1- 20     herbicidal    10                                        compound              compound                                                binding agent                                                                             0-10      lignin sulfonate                                                                            5                                         diluent(s)  70-99     calcium carbonate                                                                           85                                                    100%                    100%                                      FLOWABLE FORMULATIONS                                                         herbicidal  20-70     herbicidal    45                                        compound              compound                                                surfactant(s)                                                                             1-10      polyoxyethylene                                                                             5                                                               ether                                                   suspending agent(s)                                                                       0.05-1    attagel       0.05                                      antifreeze agent                                                                          1-10      propylene glycol                                                                            10                                        antimicrobial agent                                                                       1-10      1,2-benzisothia-                                                                            0.03                                                            zoline-3-one                                            antifoam agent                                                                            0.1-1     silicone defoamer                                                                           0.02                                      solvent     7.95-77.85                                                                              water         39.9                                                  100%                    100%                                      ______________________________________                                    

When salts are used as the active ingredient in the herbicidalcompositions of this invention it is recommended to use salts that areagriculturally acceptable.

The phytotoxic compositions of this invention can also contain otheradditives, for example, fertilizers, other herbicides and otherpesticides, used as adjuvant or in combination with any of theabovedescribed adjuvants. Fertilizers useful in combination with theactive ingredients include, for example, ammonium nitrate, urea andsuperphosphate.

What is claimed is:
 1. The method of controlling undesirable vegetationcomprising applying to the area where control is desired, anherbicidally effective amount of a compound having the formula ##STR17##wherein R is halogen; C₁ -C₂ alkyl; C₁ -C₂ alkoxy; nitro; cyano; C₁ -C₂haloalkyl; or R^(a) SO_(n) -- wherein n is 0 or 2 and R^(a) is C₁ -C₂alkyl;R¹ is hydrogen or C₁ -C₄ alkyl; R² is hydrogen or C₁ -C₄ alkyl; orR¹ and R² together are alkylene having 2-5 atoms; R³ is hydrogen or C₁-C₄ alkyl; R⁴ is hydrogen or C₁ -C₄ alkyl; or R³ and R⁴ is together arecarbonyl; and R⁵ and R⁶ independently are (1) hydrogen; (2) halogen; (3)C₁ -C₄ alkyl; (4) C₁ -C₄ alkoxy; (5) trifluoromethoxy; (6) cyano; (7)nitro; (8) C₁ -C₄ haloalkyl; (9) R^(b) SO_(m) -- wherein m is theinteger 0, 1 or 2; and R^(b) is (a) C₁ -C₄ alkyl; (b) C₁ -C₄ alkylsubstituted with halogen or cyano; (c) phenyl; or (d) benzyl; (10)--NR^(c) R^(d) wherein R^(c) and R^(d) independently are hydrogen or C₁-C₄ alkyl; (11) R^(e) C(O)-- wherein R^(e) is C₁ -C₄ alkyl or C₁ -C₄alkoxy; (12) --SO₂ NR^(c) R^(d) wherein R^(c) and R^(d) are as defined;or (13) --N(R^(c))C(O)R^(d) wherein R^(c) and R^(d) R⁷ is C₁ -C₄ alkylor phenyl; and t is the integer 1 are as defined and their salts.
 2. Themethod of claim 1 wherein R is chlorine, bromine, C₁ -C₂ alkyl, C₁ -C₂alkoxy, cyano, nitro, C₁ -C₂ alkylthio or C₁ -C₂ alkylsulfonyl; R¹ ishydrogen or methyl; R² is hydrogen or methyl; R³ is hydrogen or methyl;R⁴ is hydrogen or methyl; or R³ and R⁴ together are carbonyl; R⁵ and R⁶independently are (1) hydrogen; (2) halogen; (3) C₁ -C₄ alkyl; (4) C₁-C₄ alkoxy; (5) trifluoromethoxy; (6) cyano; (7) nitro; (8) C₁ -C₄haloalkyl; (9) R^(b) SO_(m) -- wherein m is the integer 0, 1 or 2; andR^(b) is (a) C₁ -C₄ alkyl; (b) C₁ -C₄ alkyl substituted with halogen orcyano; (c) phenyl; or (d) benzyl; (10) --NR^(c) R^(d) wherein R^(c) andR^(d) independently are hydrogen or C₁ -C₄ alkyl; (11) R³ C(O)-- whereinR^(e) is C₁ -C₄ alkyl or C₁ -C₄ alkoxy; (12) SO₂ NR^(c) R^(d) whereinR^(c) and R^(d) are as defined; or (13) --N--(R^(c))C(O)R^(d) whereinR^(c) and R^(d) are as defined; R⁷ is C₁ -C₄ alkyl; and t is theinteger
 1. 3. The method of claim 2 wherein R⁵ and R⁶ are independentlyare hydrogen; chlorine; fluorine; bromine; methyl; methoxy;trifluoromethoxy; cyano; nitro; trifluoromethyl; R^(b) SO_(m) -- whereinm is the integer 2 and R^(b) is methyl, chloromethyl, trifluoromethyl,cyanomethyl, ethyl, or n-propyl; --NR^(c) R^(d) wherein R^(c) and R^(d)independently are hydrogen or C₁ -C₄ alkyl; R^(e) C(O)-- where R^(e) isC₁ -C₄ alkyl or C₁ -C₄ alkoxy or SO₂ NR^(c) R^(d) wherein R^(c) andR^(d) are as defined and R⁵ is in the 3-position and R⁶ is in the4-position.
 4. The method of claim 2 wherein R⁵ is hydrogen and R⁶ ishydrogen, chlorine, bromine, fluorine, trifluoromethyl, cyano or R^(b)SO₂ wherein R^(b) is C₁ -C₄ alkyl or C₁ -C₄ haloalkyl.
 5. The method ofclaim 3 wherein R is nitro, R¹ is hydrogen, R² is hydrogen, R³ ishydrogen, R⁴ is hydrogen, R⁵ is hydrogen, R⁶ is 4-chlorine and R⁷ isn-propyl.
 6. The method of claim 3 wherein R is chlorine, R¹ ishydrogen, R² is hydrogen, R³ is hydrogen, R⁴ is hydrogen, R⁵ ishydrogen, R⁶ is 4-SO₂ CH₃ and R⁷ is n-propyl.
 7. The method of claim 3wherein R is nitro, R¹ is hydrogen, R² is hydrogen, R³ is hydrogen, R⁴is hydrogen, R⁵ i hydrogen, R⁶ is 4-chlorine and R⁷ is ethyl.
 8. Themethod of claim 3 wherein R is nitro, R¹ is methyl, R² is hydrogen, R³is hydrogen, R⁴ is hydrogen, R⁵ is hydrogen, R⁶ is 4-chlorine, and R⁷ ismethyl.
 9. The method of claim 3 wherein R is nitro, R¹ is hydrogen, R²is hydrogen, R³ is methyl, R⁴ is methyl, R⁵ is hydrogen, R⁶ is4-chlorine and R⁷ is methyl.
 10. The method of claim 3 wherein R isnitro, R¹ is methyl, R² is hydrogen, R³ is hydrogen, R⁴ is hydrogen, R⁵is hydrogen, R⁶ is 4-SO₂ CH₂ Cl, and R⁷ is ethyl.
 11. The method ofclaim 3 wherein R is nitro, R¹ is methyl, R² is hydrogen, R³ ishydrogen, R⁴ is hydrogen, R⁵ is hydrogen, R⁶ is 4-SO₂ CH₂ Cl and R⁷ ismethyl.
 12. The method of claim 3 wherein R is nitro, R¹ is methyl, R²is hydrogen, R³ is hydrogen, R⁴ is hydrogen, R⁵ is hydrogen, R⁶ is 4-SO₂CH₃ and R⁷ is ethyl.
 13. The method of claim 2 wherein R⁵ is hydrogen.14. The method of claim 3 wherein R⁵ is hydrogen.
 15. An herbicidalcomposition comprising an herbicidally active 3-(benzoyl)-4-oxolactam ortheir salts and an inert carrier therefor.
 16. The herbicidalcomposition of claim 15 wherein the 3-(benzoyl)-4-oxolactam is acompound of the formula ##STR18## wherein R is halogen; C₁ -C₂ alkyl; C₁-C₂ alkoxy; nitro; cyano; C₁ -C₂ haloalkyl; or R^(a) SO_(n) -- wherein nis 0 or 2 and R^(a) is C₁ -C₂ alkyl;R¹ is hydrogen or C₁ -C₄ alkyl; R²is hydrogen or C₁ -C₄ alkyl; or R¹ and R² together are alkylene having2-5 carbon atoms; R³ is hydrogen or C₁ -C₄ alkyl; R⁴ is hydrogen or C₁-C₄ alkyl; or R³ and R⁴ together are carbonyl; and R⁵ and R⁶independently are (1) hydrogen; (2) halogen; (3) C₁ -C₄ alkyl; (4) C₁-C₄ alkoxy; (5) trifluoromethyl; (6) cyano; (7) nitro; (8) C₁ -C₄haloalkyl; (9) R^(b) SO_(m) -- wherein m is the integer 0, 1 or 2; andR^(b) is (a) C₁ -C₄ alkyl; (b) C₁ -C₄ alkyl subtituted with halogen orcyano; (c) phenyl; or (d) benzyl; (10) --NR^(c) R^(d) wherein R^(c) andR^(d) independently are hydrogen or C₁ -C₄ alkyl; (11) R^(e) C(O)--wherein R^(e) is C₁ -C₄ alkyl or C₁ -C₄ alkoxy; or (12) --SO₂ NR^(c)R^(d) wherein R^(c) and R^(d) are as defined; and (13) --N(R^(c))C(O)R^(d) wherein R^(c) and R^(d) are as defined; R⁷ is C₁ -C₄ alkyl orphenyl; and t is the integer 1 and their salts.
 17. The composition ofclaim 16 wherein R is chlorine, bromine, C₁ -C₂ alkyl, C₁ -C₂ alkoxy,cyano, nitro, C₁ -C₂ alkylthio or C₁ -C₂ alkylsulfonyl; R¹ is hydrogenor methyl; R² is hydrogen or methyl; R³ is hydrogen or methyl; R⁴ ishydrogen or methyl; or R³ and R⁴ together are carbonyl; R⁵ and R⁶independently are (1) hydrogen; (2) halogen; (3) C₁ -C₄ alkyl; (4) C₁-C₄ alkoxy; (5) trifluoromethoxy; (6) cyano; (7) nitro; (8) C₁ -C₄haloalkyl; (9) R^(b) SO_(m) -- wherein m is the integer 0, 1 or 2; andR^(b) is (a) C₁ -C₄ alkyl; (b) C₁ -C₄ alkyl substituted with halogen orcyano; (c) phenyl; or (d) benzyl; (10) --NR^(c) R^(d) wherein R^(c) andR^(d) independently are hydrogen or C₁ -C₄ alkyl; hydrogen or C₁ -C₄alkyl; (11) R^(e) C(O)-- wherein R^(e) is C₁ -C₄ alkyl or C₁ -C₄ alkoxy;(12) SO₂ NR^(c) R^(d) wherein R^(c) and R^(d) are as defined; or (13)--N--(R^(c))C(O)R^(d) wherein R^(c) and R^(d) are as defined; R⁷ is C₁-C₄ alkyl; and t is
 1. 18. The composition of claim 17 wherein R⁵ and R⁶are independently are hydrogen; chlorine; fluorine; bromine; methyl;methoxy; trifluoromethoxy; cyano; nitro; trifluoromethyl; R^(b) SO_(n)-- wherein n is the integer 2 and R^(b) is methyl, chloromethyl,trifluoromethyl, cyanomethyl, ethyl, or n-propyl; --NR^(c) R^(d) whereinR^(c) and R^(d) independently are hydrogen or C₁ -C₄ alkyl; R^(e) C(O)--where R^(e) is C₁ -C₄ alkyl or C₁ -C₄ alkoxy or SO₂ N wherein R^(c) andR^(d) are as defined and R⁵ is in the 3-position and R⁶ is in the4-position.
 19. The composition of claim 17 wherein R⁵ is hydrogen andR⁶ is hydrogen, chlorine, bromine, fluorine, trifluoromethyl, cyano orR^(b) SO₂ wherein R^(b) is C₁ -C₄ alkyl or C₁ -C₄ haloalkyl.
 20. Thecomposition of claim 16 wherein R is nitro, R¹ is hydrogen, R² ishydrogen, R³ is hydrogen, R⁴ is hydrogen, R⁵ is hydrogen, R⁶ is4-chlorine and R⁷ is n-C₃ H₇.
 21. The composition of claim 16 wherein Ris chlorine, R¹ is hydrogen, R² is hydrogen, R³ is hydrogen, R⁴ ishydrogen, R⁵ is hydrogen, R⁶ is 4-SO₂ CH₃ and R⁷ is n-propyl.
 22. Thecomposition of claim 16 wherein R is nitro, R¹ is hydrogen, R² ishydrogen, R³ is hydrogen, R⁴ is hydrogen, R⁵ is hydrogen, R⁶ is4-chlorine and R⁷ is ethyl.
 23. The composition of claim 16 wherein R isnitro, R¹ is methyl, R² is hydrogen, R³ is hydrogen, R⁴ is hydrogen, R⁵is hydrogen, R⁶ is 4-chlorine, and R⁷ is methyl.
 24. The composition ofclaim 16 wherein R is nitro, R¹ is hydrogen, R² is hydrogen, R³ ismethyl, R⁴ is methyl, R⁵ is hydrogen, R⁶ is 4-chlorine and R⁷ is methyl.25. The composition of claim 16 wherein R is nitro, R¹ is methyl, R² ishydrogen, R³ is hydrogen, R⁴ is hydrogen, R⁵ is hydrogen, R⁶ is 4-SO₂CH₂ Cl, and R⁷ is ethyl.
 26. The composition of claim 16 wherein R isnitro, R¹ is methyl, R² is hydrogen, R³ is hydrogen, R⁴ is hydrogen, R⁵is hydrogen, R⁶ is 4-SO₂ CH₂ Cl and R⁷ is CH₃.
 27. The composition ofclaim 16 wherein R is nitro, R¹ is methyl, R² is hydrogen, R³ ishydrogen, R⁴ is hydrogen, R⁵ is hydrogen, R⁶ is 4-SO₂ CH₃ and R⁷ isethyl.
 28. The composition of claim 17 wherein R⁵ is hydrogen.
 29. Thecomposition of claim 17 wherein R⁵ is hydrogen.
 30. The method ofcontrolling undesirable vegetation comprising applying to the area wherecontrol is desired, an herbicidal composition comprising an herbicidallyactive 3-(benzoyl)-4-oxolactam or their salts and an inert carriertherefor.
 31. The method of claim 30 wherein the 3-(benzoyl)-4-oxolactamis a compound of the formula ##STR19## wherein R is halogen; C₁ -C₂alkyl; nitro; cyano; C₁ -C₂ haloalkyl; or R^(a) SO_(n) -- wherein n is 0or 2 and R^(a) is C₁ -C₂ alkyl;R¹ is hydrogen or C₁ -C₄ alkyl; R² ishydrogen or C₁ -C₄ alkyl; or R¹ and R² together are alkylene having 2-5carbon atoms; R³ is hydrogen or C₁ -C₄ alkyl; R⁴ is hydrogen or C₁ -C₄alkyl; or R³ and R⁴ together are carbonyl; and R⁵ and R⁶ independentlyare (1) hydrogen; (2) halogen; (3) C8) alkyl; (4) C₁ -C₄ alkoxy; (5)trifluoromethoxy; (6) cyano; (7) nitro; (C₁ -C₄ haloalkyl; (9) R^(b)SO_(m) -- wherein m is the integer 0, 1 or 2; and R^(b) is (a) C₁ -C₄alkyl; (b) C₁ -C₄ alkyl substituted with halogen or cyano; (c) phenyl;or (d) benzyl; (10) --NR^(c) R^(d) wherein R^(c) and R^(d) independentlyare hydrogen or C₁ -C₄ alkyl; (11) R^(e) C(O)-- wherein R^(e) is C₁ -C₄alkyl or C₁ -C₄ alkoxy; or (12) --SO₂ NR^(c) R^(d) wherein R^(c) andR^(d) are as defined; and (13) --N(R^(c))C(O)R^(d) wherein R^(c) andR^(d) are as defined; R⁷ is C₁ -C₄ alkyl or phenyl; and t is the integer1.